490 



Reviews — Barrandds Silurian Cephalopoda. 



The following list will express the relative numbers described from 

 the various geographical regions enumerated in the work before us : — 





Geographical Areas of the Silurian 



Number 



of 

 Genera. 



Number 



of 

 Species. 





Cephalopoda. 



A 1 ^ 

 ^ \ 2 



Bohemia ... 



20 



979 



France, Spain, Portugal, and Sardinia... 



4 



35 



' 3 



England, Scotland, and Ireland 



10 



92 



4 



Norway ... 



9 



33 



Bl< 6 



Sweden ... 



7 



35 



Russia 



10 



107 





7 



Thuringia, Franconia, Saxony, the Hartz, Germany | 

 andHolland ... ... ... ... j 



7 



76 





. 8 





^ 9 



Newfoundland 



6 



23 





10 



Acadia 



4 



10 





11 



Canada (Anticosti) ... 



14 



171 





12 



New Brunswick 



1 



3 



B2< 



13 



New York 



9 



127 



14 



"Wisconsin 



10 



58 





15 



Illinois 



8 



29 





16 



Missouri ... 



3 



11 





17 



Vermont, Michigan, Pennsylvania, Iowa, Min- 1 

 nesota and Arctic America ... ... . . . ; 



5 



31 





LIS 







C 



fl9 

 (20 



Himalayas 



4 



6 



Tasmania 



2 



6 



A = Grand central zone of Europe. 

 B = Grand northern zone. 



B 1 = European section. 

 B 2 = American section. 



C = Divers countries. 



A careful examination of the above elaborately worked out 

 statistics of this group, published by M. Barrande, will show that 

 exactly in proportion to the labour bestowed so is the result. 



Thus we see that Barrande in Bohemia ; Kjeriilf and Angelin in 

 Norway and Sweden; Strangways, Murchison, and Schmidt in 

 Eussia; Billings and Hall in America; and Sowerby, Salter, 

 Phillips, Portlock, M'Coy and other paleontologists in England, 

 have brought up the genera and species in these areas to the high 

 total numbers we have indicated, and we may assiime that, given an 

 equally large number of ardent and earnest paleontologists in all 

 the other Silurian countries, explored and unexplored, we might 

 expect equally great results. 



Taking however a geologically coloured map of the world, and 

 contrasting the relative proportion of the Silurian areas already ex- 

 plored with the vast and unexplored regions yet remaining, we 

 cannot but conclude, that after all, M. Barrande, like every other 

 generalizer, has prepared his tables and based his results on the 

 limited information we at present possess, and we may therefore 

 fairly conclude that, however carefully prepared, these generalizations 

 must necessarily be very imperfect. What, for instance, do we yet 

 know of the Primordial Silurian forms to justify us in assuming that 

 we shall not find Orthocerata in these rocks ? 



Nor should we, as zoologists, forget that the argument derived 



